ISL12027

® ISL12027 New Features Data Sheet October 18, 2006 FN8232.4 Real Time Clock/Calendar with EEPROM The ISL12027 device is a low power real time clock with timing and crystal compensation, clock/calender, power-fail indicator, two periodic or polled alarms, intelligent battery backup switching, CPU Supervisor and integrated 512 x 8 bit EEPROM, in 16 Byte per page format. The oscillator uses an external, low-cost 32.768kHz crystal. The real time clock tracks time with separate registers for hours, minutes, and seconds. The device has calendar registers for date, month, year and day of the week. The calendar is accurate through 2099, with automatic leap year correction. Features • Real Time Clock/Calendar - Tracks Time in Hours, Minutes, and Seconds - Day of the Week, Day, Month, and Year • Two Non-Volatile Alarms - Settable on the Second, Minute, Hour, Day of the Week, Day, or Month - Repeat Mode (periodic interrupts) • Automatic Backup to Battery or SuperCap • On-Chip Oscillator Compensation - Internal Feedback Resistor and Compensation Capacitors - 64 Position Digitally Controlled Trim Capacitor - 6 Digital Frequency Adjustment Settings to ±30ppm • 512 x 8 Bits of EEPROM - 16-Byte Page Write Mode (32 total pages) - 8 Modes of Block Lock™ Protection - Single Byte Write Capability • High Reliability - Data Retention: 50 years - Endurance: >2,000,000 Cycles Per Byte • I2C* Interface - 400kHz Data Transfer Rate Pinouts ISL12027 (8 LD TSSOP) TOP VIEW VBAT VDD X1 X2 1 2 3 4 8 7 6 5 SCL SDA GND RESET ISL12027 (8 LD SOIC) TOP VIEW X1 X2 RESET GND 1 2 3 4 8 7 6 5 VDD VBAT SCL SDA • 800nA Battery Supply Current • Package Options - 8 Ld SOIC and 8 Ld TSSOP Packages • Pb-Free Plus Anneal Available (RoHS Compliant) Applications • Utility Meters • HVAC Equipment • Audio/Video Components • Modems • Network Routers, Hubs, Switches, Bridges • Cellular Infrastructure Equipment • Fixed Broadband Wireless Equipment • Pagers/PDA • POS Equipment • Test Meters/Fixtures • Office Automation (Copiers, Fax) • Home Appliances • Computer Products • Other Industrial/Medical/Automotive 1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc. *I2C is a Trademark of Philips. Copyright Intersil Americas Inc. 2005, 2006. All Rights Reserved All other trademarks mentioned are the property of their respective owners. ISL12027 Ordering Information PART NUMBER (Note) ISL12027IB27Z ISL12027IB27AZ ISL12027IB30AZ ISL12027IBZ ISL12027IBAZ ISL12027IV27Z ISL12027IV27AZ ISL12027IV30AZ ISL12027IVZ ISL12027IVAZ PART MARKING 12027IB27Z 12027IB27AZ 12027IB30AZ 12027IBZ 12027IBAZ 2027I27Z 202727AZ 202730AZ 2027IVZ 2027IVAZ VRESET VOLTAGE 2.63V 2.92V 3.09V 4.38V 4.64V 2.63V 2.92V 3.09V 4.38V 4.64V TEMP. RANGE (°C) -40 to +85 -40 to +85 -40 to +85 -40 to +85 -40 to +85 -40 to +85 -40 to +85 -40 to +85 -40 to +85 -40 to +85 PACKAGE (Pb-Free) 8 Ld SOIC 8 Ld SOIC 8 Ld SOIC 8 Ld SOIC 8 Ld SOIC 8 Ld TSSOP 8 Ld TSSOP 8 Ld TSSOP 8 Ld TSSOP 8 Ld TSSOP PKG DWG. # M8.15 M8.15 M8.15 M8.15 M8.15 M8.173 M8.173 M8.173 M8.173 M8.173 NOTE: Intersil Pb-free plus anneal products employ special Pb-free material sets; molding compounds/die attach materials and 100% matte tin plate termination finish, which are RoHS compliant and compatible with both SnPb and Pb-free soldering operations. Intersil Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020. Add “-T” suffix for tape and reel. Block Diagram OSC Compensation 32.768kHz X1 X2 Oscillator Frequency Divider 1Hz Timer Calendar Logic Time Keeping Registers (SRAM) Battery Switch Circuitry VDD VBAT SCL SDA Mask Serial Interface Decoder Control Decode Logic Control/ Registers (EEPROM) Status Registers (SRAM) Alarm Compare Alarm Regs (EEPROM) 4K EEPROM ARRAY 8 RESET Watchdog Timer Low Voltage Reset 2 FN8232.4 October 18, 2006 ISL12027 Pin Descriptions PIN NUMBER SOIC 1 2 3 TSSOP 3 4 5 SYMBOL X1 X2 RESET BRIEF DESCRIPTION The X1 pin is the input of an inverting amplifier and is intended to be connected to one pin of an external 32.768kHz quartz crystal. X1 can also be driven directly from a 32.768kHz source. The X2 pin is the output of an inverting amplifier and is intended to be connected to one pin of an external 32.768kHz quartz crystal. RESET. This is a reset signal output. This signal notifies a host processor that the “watchdog” time period has expired or that the voltage has dropped below a fixed VTRIP threshold. It is an open drain active LOW output. Recommended value for the pull-up resistor is 5kΩ, If unused, connect to ground. Ground. Serial Data (SDA) is a bidirectional pin used to transfer serial data into and out of the device. It has an open drain output and may be wire OR’ed with other open drain or open collector outputs. The Serial Clock (SCL) input is used to clock all serial data into and out of the device. The input buffer on this pin is always active (not gated). This input provides a backup supply voltage to the device. VBAT supplies power to the device in the event that the VDD supply fails. This pin should be tied to ground if not used. Power Supply. 4 5 6 7 8 6 7 8 1 2 GND SDA SCL VBAT VDD 3 FN8232.4 October 18, 2006 ISL12027 Absolute Maximum Ratings Voltage on VDD, VBAT, SCL, SDA, and RESET pins (respect to ground) . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6.0V Voltage on X1 and X2 pins (respect to ground) . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 2.5V Latchup (Note 1) . . . . . . . . . . . . . . . . . . . Class II, Level B @ +85°C ESD Rating (MIL-STD-883, Method 3014) . . . . . . . . . . . . . . .>±2kV ESD Rating (Machine Model) . . . . . . . . . . . . . . . . . . . . . . . . .>175V Thermal Information Thermal Resistance (Note 2) θJA (°C/W) 8 Ld SOIC Package . . . . . . . . . . . . . . . . . . . . . . . . . 120 8 Ld TSSOP Package . . . . . . . . . . . . . . . . . . . . . . . 140 Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . .-65°C to +150°C Lead Temperature (Soldering, 10s) . . . . . . . . . . . . . . . . . . . . . 300°C CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. NOTES: 1. Jedec Class II pulse conditions and failure criterion used. Level B exceptions are: Using a max positive pulse of 8.35V on all pins except X1 and X2, Using a max positive pulse of 2.75V on X1 and X2, and using a max negative pulse of -1V for all pins. 2. θJA is measured with the component mounted on a high effective thermal conductivity test board in free air. See Tech Brief TB379 for details. DC Electrical Specifications SYMBOL VDD VBAT PARAMETER Main Power Supply Backup Power Supply Unless otherwise noted, VDD = +2.7V to +5.5V, TA = -40°C to +85°C, Typical values are at TA = 25°C and VDD = 3.3V CONDITIONS MIN 2.7 1.8 TYP MAX 5.5 5.5 UNIT V V NOTES Electrical Specifications SYMBOL IDD1 PARAMETER Supply Current with I2C Active CONDITIONS VDD = 2.7V VDD = 5.5V IDD2 Supply Current for Non-Volatile Programming Supply Current for Main Timekeeping (Low Power Mode) Battery Supply Current VDD = 2.7V VDD = 5.5V VDD = VSDA = VSCL = 2.7V VDD = VSDA = VSCL = 5.5V VBAT = 1.8V, VDD = VSDA = VSCL= VRESET = 0V VBAT = 3.0V, VDD = VSDA = VSCL= VRESET = 0V IBATLKG VTRIP Battery Input Leakage VBAT Mode Threshold VDD = 5.5V, VBAT = 1.8V -100 1.8 2.2 30 50 10 800 850 MIN TYP MAX 500 800 2.5 3.5 10 20 1000 1200 100 2.6 UNIT µA µA mA mA µA µA nA nA nA V mV mV V/ms 7 7, 10 7, 10 8 3, 6, 7 3, 4, 5 NOTES 3, 4, 5 ,3 5 IDD3 IBAT VTRIPHYS VTRIP Hysteresis VBATHYS VDD SRVBAT Hysteresis VDD Negative Slew rate RESET OUTPUT VOL Output Low Voltage VDD = 5.5V IOL = 3mA VDD = 2.7V IOL = 1mA ILO Output Leakage Current VDD = 5.5V VOUT = 5.5V 100 0.4 0.4 400 V V nA 4 FN8232.4 October 18, 2006 ISL12027 Watchdog Timer/Low Voltage Reset Parameters SYMBOL tRPD tPURST VRVALID VRESET PARAMETER VDD Detect to RESET LOW Power-up Reset Time-Out Delay Minimum VDD for Valid RESET Output ISL12027-4.5A Reset Voltage Level ISL12027 Reset Voltage Level ISL12027-3 Reset Voltage Level ISL12027-2.7A Reset Voltage Level ISL12027-2.7 Reset Voltage Level tWDO Watchdog Timer Period 32.768kHz crystal between X1 and X2 100 1.0 4.59 4.33 3.04 2.87 2.58 1.70 725 225 tRST tRSP Watchdog Timer Reset Time-Out Delay I2C Interface Minimum Restart Time 32.768kHz crystal between X1 and X2 225 1.2 4.64 4.38 3.09 2.92 2.63 1.75 750 250 250 4.69 4.43 3.14 2.97 2.68 1.801 775 275 275 CONDITIONS MIN TYP (Note 5) 500 250 400 MAX UNITS ns ms V V V V V V s ms ms ms µs NOTES 9 EEPROM SPECIFICATIONS EEPROM Endurance EEPROM Retention Temperature ≤75°C >2,000,000 50 Cycles Years Serial Interface (I2C) Specifications SYMBOL VIL VIH PARAMETER SDA, and SCL Input Buffer LOW Voltage SDA, and SCL Input Buffer HIGH Voltage CONDITIONS SBIB = 1 (Under VDD mode) SBIB = 1 (Under VDD mode) SBIB = 1 (Under VDD mode) IOL = 4mA VIN = 5.5V VIN = 5.5V MIN -0.3 0.7 x VDD 0.05 x VDD 0 0.1 0.1 0.4 10 10 TYP MAX 0.3 x VDD VDD + 0.3 UNITS V V V V µA µA NOTES Hysteresis SDA and SCL Input Buffer Hysteresis VOL ILI ILO SDA Output Buffer LOW Voltage Input Leakage Current on SCL I/O Leakage Current on SDA TIMING CHARACTERISTICS fSCL tIN tAA SCL Frequency Pulse Width Suppression Time at SDA and SCL Inputs SCL Falling Edge to SDA Output Data Valid Time the Bus Must be Free Before the Start of a New Transmission Any pulse narrower than the max spec is suppressed. SCL falling edge crossing 30% of VDD, until SDA exits the 30% to 70% of VDD window. SDA crossing 70% of VDD during a STOP condition, to SDA crossing 70% of VDD during the following START condition. Measured at the 30% of VDD crossing. Measured at the 70% of VDD crossing. 1300 400 50 900 kHz ns ns tBUF ns tLOW tHIGH Clock LOW Time Clock HIGH Time 1300 600 ns ns 5 FN8232.4 October 18, 2006 ISL12027 Serial Interface (I2C) Specifications (Continued) SYMBOL tSU:STA tHD:STA PARAMETER START Condition Setup Time START Condition Hold Time CONDITIONS SCL rising edge to SDA falling edge. Both crossing 70% of VDD. From SDA falling edge crossing 30% of VDD to SCL falling edge crossing 70% of VDD. From SDA exiting the 30% to 70% of VDD window, to SCL rising edge crossing 30% of VDD. From SCL falling edge crossing 70% of VDD to SDA entering the 30% to 70% of VDD window. From SCL rising edge crossing 70% of VDD, to SDA rising edge crossing 30% of VDD. From SDA rising edge to SCL falling edge. Both crossing 70% of VDD. From SCL falling edge crossing 30% of VDD, until SDA enters the 30% to 70% of VDD window. From 30% to 70% of VDD From 70% to 30% of VDD Total on-chip and off-chip MIN 600 600 TYP MAX UNITS ns ns NOTES tSU:DAT Input Data Setup Time 100 ns tHD:DAT Input Data Hold Time 0 ns tSU:STO STOP Condition Setup Time 600 ns tHD:STO tDH STOP Condition Hold Time for Read, or Volatile Only Write Output Data Hold Time 600 0 ns ns tR tF Cb Cpin tWC NOTES: SDA and SCL Rise Time SDA and SCL Fall Time Capacitive loading of SDA or SCL SDA, and SCL Pin Capacitance Non-Volatile Write Cycle Time 20 + 0.1 x Cb 20 + 0.1 x Cb 10 250 250 400 10 12 20 ns ns pF pF ms 10 3. RESET Inactive (no reset). 4. VIL = VDD x 0.1, VIH = VDD x 0.9, fSCL = 400kHz. 5. VRESET = 2.63V (VDD must be greater than VRESET), VBAT = 0V. 6. Bit BSW = 0 (Standard Mode), VBAT ≥ 1.8V. 7. Specified at 25°C. 8. In order to ensure proper timekeeping, the VDD SR- specification must be followed. 9. Parameter is not 100% tested. 10. tWC is the minimum cycle time to be allowed for any non-volatile Write by the user, it is the time from valid STOP condition at the end of Write sequence of a serial interface Write operation, to the end of the self-timed internal non-volatile write cycle. 6 FN8232.4 October 18, 2006 ISL12027 Timing Diagrams tF tHIGH tLOW tR tHD:STO SCL tSU:STA tHD:STA SDA (INPUT TIMING) tSU:DAT tHD:DAT tSU:STO tAA SDA (OUTPUT TIMING) tDH tBUF FIGURE 1. BUS TIMING SCL SDA 8TH BIT OF LAST BYTE ACK tWC STOP CONDITION START CONDITION FIGURE 2. WRITE CYCLE TIMING tRSP tRSPtWDO tRST tRSP>tWDO tRST SCL SDA RESET START STOP START Note: All inputs are ignored during the active reset period (tRST). FIGURE 3. WATCHDOG TIMING VRESET VDD tPURST tRPD tR RESET tF VRVALID tPURST FIGURE 4. RESET TIMING 7 FN8232.4 October 18, 2006 ISL12027 Typical Performance Curves 4.00 3.50 3.00 2.50 2.00 1.50 1.00 0.50 0.00 1.8 Temperature is 25°C unless otherwise specified 0.90 0.80 BSW = 0 or 1 0.70 SCL,SDA pullups = 0V 0.60 0.50 0.40 0.30 SCL,SDA pullups = 0V BSW = 0 or 1 Ibat (uA) SCL,SDA pullups = Vbat 0.20 BSW = 0 or 1 2.3 2.8 3.3 3.8 4.3 4.8 5.3 Ibat 0.10 0.00 1.80 2.30 2.80 3.30 3.80 4.30 4.80 5.30 Vbat (V) Vbat(V) FIGURE 5. IBAT vs VBAT, SBIB = 0 FIGURE 6. IBAT vs VBAT, SBIB = 1 5.00 4.50 4.00 3.50 1.40 Vdd=5.5V 1.20 Vbat = 3.0V 1.00 Ibat (uA) 45 55 65 75 85 Idd (uA) 3.00 2.50 2.00 1.50 1.00 Vdd=3.3V 0.80 0.60 0.40 0.20 0.50 0.00 -45 0.00 -45 -35 -25 -15 -5 5 15 25 35 -35 -25 -15 -5 5 15 25 35 45 55 65 75 85 Temperature Temperature FIGURE 7. IDD3 vs TEMPERATURE FIGURE 8. IBAT vs TEMPERATURE 4.50 4.00 80 60 3.50 3.00 PPM change from ATR=0 2.3 2.8 3.3 3.8 4.3 4.8 5.3 40 Idd (uA) 2.50 2.00 1.50 1.00 0.50 0.00 1.8 20 0 -20 -40 -32 -28 -24 -20 -16 -12 -8 -4 0 4 8 12 16 20 24 28 Vdd (V) ATR setting FIGURE 9. IDD3 vs VDD FIGURE 10. ∆FOUT vs ATR SETTING 8 FN8232.4 October 18, 2006 ISL12027 Description The ISL12027 device is a Real Time Clock with clock/ calendar, two polled alarms with integrated 512x8 EEPROM configured in 16 Byte per page format, oscillator compensation, CPU Supervisor (Power on Reset, Low Voltage Sensing and Watchdog Timer) and battery backup switch. The oscillator uses an external, low-cost 32.768kHz crystal. All compensation and trim components are integrated on the chip. This eliminates several external discrete components and a trim capacitor, saving board area and component cost. The Real-Time Clock keeps track of time with separate registers for Hours, Minutes, Seconds. The Calendar has separate registers for Date, Month, Year and Day-of-week. The calendar is correct through 2099, with automatic leap year correction. The Dual Alarms can be set to any Clock/Calendar value for a match. For instance, every minute, every Tuesday, or 5:23 AM on March 21. The alarms can be polled in the Status Register. There is a repeat mode for the alarms allowing a periodic interrupt. The ISL12027 device integrates CPU Supervisory functions (POR, WDT) and Battery Switch. There is Power-On-Reset (RESET) output with 250ms delay from power on. It will also assert RESET when VDD goes below the specified threshold. The Vtrip threshold is selectable via VTS2/VTS1/ VTS0 registers to five (5) preselected levels. There is WatchDog Timer (WDT) with 3 selectable time-out periods (0.25s, 0.75s and 1.75s) and disabled setting. The WatchDog Timer activates the RESET pin when it expires. The device offers a backup power input pin. This VBAT pin allows the device to be backed up by battery or SuperCap. The entire ISL12027 device is fully operational from 2.7 to 5.5V and the clock/calendar portion of the ISL12027 device remains fully operational down to 1.8V (Standby Mode). The ISL12027 device provides 4k bits of EEPROM with 8 modes of BlockLock™ control. The BlockLock allows a safe, secure memory for critical user and configuration data, while allowing a large user storage area. This open drain output requires the use of a pull-up resistor. The pull-up resistor on this pin must use the same voltage source as VDD. The output circuitry controls the fall time of the output signal with the use of a slope controlled pulldown. The circuit is designed for 400kHz I2C interface speed. VBAT This input provides a backup supply voltage to the device. VBAT supplies power to the device in the event the VDD supply fails. This pin can be connected to a battery, a SuperCap or tied to ground if not used. RESET The RESET signal output can be used to notify a host processor that the watchdog timer has expired or the VDD voltage supply has dipped below the VRESET threshold. It is an open drain, active LOW output. Recommended value for the pull-up resistor is 10kΩ. If unused it can be tied to ground. X1, X2 The X1 and X2 pins are the input and output, respectively, of an inverting amplifier. An external 32.768kHz quartz crystal is used with the ISL12027 to supply a timebase for the real time clock. Internal compensation circuitry provides high accuracy over the operating temperature range from -40°C to +85°C. This oscillator compensation network can be used to calibrate the crystal timing accuracy over temperature either during manufacturing or with an external temperature sensor and microcontroller for active compensation. X2 is intended to drive a crystal only, and should not drive any external circuit (Figure 11). NO EXTERNAL COMPENSATION RESISTORS OR CAPACITORS ARE NEEDED OR ARE RECOMMENDED TO BE CONNECTED TO THE X1 AND X2 PINS. X1 X2 FIGURE 11. RECOMMENDED CRYSTAL CONNECTION Pin Descriptions Serial Clock (SCL) The SCL input is used to clock all data into and out of the device. The input buffer on this pin is always active (not gated). The pull-up resistor on this pin must use the same voltage source as VDD. Real Time Clock Operation The Real Time Clock (RTC) uses an external 32.768kHz quartz crystal to maintain an accurate internal representation of the second, minute, hour, day, date, month, and year. The RTC has leap-year correction. The clock also corrects for months having fewer than 31 days and has a bit that controls 24 hour or AM/PM format. When the ISL12027 powers up after the loss of both VDD and VBAT, the clock will not operate until at least one byte is written to the clock register. Serial Data (SDA) SDA is a bidirectional pin used to transfer data into and out of the device. It has an open drain output and may be wire ORed with other open drain or open collector outputs. The input buffer is always active (not gated). 9 FN8232.4 October 18, 2006 ISL12027 Reading the Real Time Clock The RTC is read by initiating a Read command and specifying the address corresponding to the register of the Real Time Clock. The RTC Registers can then be read in a Sequential Read Mode. Since the clock runs continuously and read takes a finite amount of time, there is a possibility that the clock could change during the course of a read operation. In this device, the time is latched by the read command (falling edge of the clock on the ACK bit prior to RTC data output) into a separate latch to avoid time changes during the read operation. The clock continues to run. Alarms occurring during a read are unaffected by the read operation. CCR Access The contents of the CCR can be modified by performing a byte or a page write operation directly to any address in the CCR. Prior to writing to the CCR (except the status register), however, the WEL and RWEL bits must be set using a three step process (See section “Writing to the Clock/Control Registers.”) The CCR is divided into 5 sections. These are: 1. Alarm 0 (8 bytes; non-volatile) 2. Alarm 1 (8 bytes; non-volatile) 3. Control (5 bytes; non-volatile) 4. Real Time Clock (8 bytes; volatile) 5. Status (1 byte; volatile) Each register is read and written through buffers. The nonvolatile portion (or the counter portion of the RTC) is updated only if RWEL is set and only after a valid write operation and stop bit. A sequential read or page write operation provides access to the contents of only one section of the CCR per operation. Access to another section requires a new operation. A read or write can begin at any address in the CCR. It is not necessary to set the RWEL bit prior to writing the status register. Section 5 (status register) supports a single byte read or write only. Continued reads or writes from this section terminates the operation. The state of the CCR can be read by performing a random read at any address in the CCR at any time. This returns the contents of that register location. Additional registers are read by performing a sequential read. The read instruction latches all Clock registers into a buffer, so an update of the clock does not change the time being read. A sequential read of the CCR will not result in the output of data from the memory array. At the end of a read, the master supplies a stop condition to end the operation and free the bus. After a read of the CCR, the address remains at the previous address +1 so the user can execute a current address read of the CCR and continue reading the next Register. Writing to the Real Time Clock The time and date may be set by writing to the RTC registers. RTC Register should be written ONLY with Page Write. To avoid changing the current time by an uncompleted write operation, write to the all 8 bytes in one write operation. When writing the RTC registers, the new time value is loaded into a separate buffer at the falling edge of the clock during the Acknowledge. This new RTC value is loaded into the RTC Register by a stop bit at the end of a valid write sequence. An invalid write operation aborts the time update procedure and the contents of the buffer are discarded. After a valid write operation, the RTC will reflect the newly loaded data beginning with the next “one second” clock cycle after the stop bit is written. The RTC continues to update the time while an RTC register write is in progress and the RTC continues to run during any non-volatile write sequences. Accuracy of the Real Time Clock The accuracy of the Real Time Clock depends on the accuracy of the quartz crystal that is used as the time base for the RTC. Since the resonant frequency of a crystal is temperature dependent, the RTC performance will also be dependent upon temperature. The frequency deviation of the crystal is a function of the turnover temperature of the crystal from the crystal’s nominal frequency. For example, a >20ppm frequency deviation translates into an accuracy of >1 minute per month. These parameters are available from the crystal manufacturer. Intersil’s RTC family provides onchip crystal compensation networks to adjust loadcapacitance to tune oscillator frequency from -34ppm to +80ppm when using a 12.5pF load crystal. For more detailed information see the Application section. Real Time Clock Registers (Volatile) SC, MN, HR, DT, MO, YR: Clock/Calendar Registers These registers depict BCD representations of the time. As such, SC (Seconds) and MN (Minutes) range from 00 to 59, HR (Hour) is 1 to 12 with an AM or PM indicator (H21 bit) or 0 to 23 (with MIL = 1), DT (Date) is 1 to 31, MO (Month) is 1 to 12, YR (Year) is 0 to 99. Clock/Control Registers (CCR) The Control/Clock Registers are located in an area separate from the EEPROM array and are only accessible following a slave byte of “1101111x” and reads or writes to addresses [0000h:003Fh]. The clock/control memory map has memory addresses from 0000h to 003Fh. The defined addresses are described in the Table 2. Writing to and reading from the undefined addresses are not recommended. 10 FN8232.4 October 18, 2006 ISL12027 DW: Day of the Week Register This register provides a Day of the Week status and uses three bits DY2 to DY0 to represent the seven days of the week. The counter advances in the cycle 0-1-2-3-4-5-6-0-12-… The assignment of a numerical value to a specific day of the week is arbitrary and may be decided by the system software designer. The default value is defined as ‘0’. OSCF: Oscillator Fail Indicator This bit is set to “1” if the oscillator is not operating. The bit is set to “0” only if the oscillator is functioning. This bit is read only, and is set/reset by hardware. RWEL: Register Write Enable Latch This bit is a volatile latch that powers up in the LOW (disabled) state. The RWEL bit must be set to “1” prior to any writes to the Clock/Control Registers. Writes to RWEL bit do not cause a non-volatile write cycle, so the device is ready for the next operation immediately after the stop condition. A write to the CCR requires both the RWEL and WEL bits to be set in a specific sequence. Y2K: Year 2000 Register Can have value 19 or 20. As of the date of the introduction of this device, there would be no real use for the value 19 in a true real time clock, however. 24 Hour Time If the MIL bit of the HR register is 1, the RTC uses a 24-hour format. If the MIL bit is 0, the RTC uses a 12-hour format and H21 bit functions as an AM/PM indicator with a ‘1’, representing PM. The clock defaults to standard time with H21 = 0. WEL: Write Enable Latch The WEL bit controls the access to the CCR during a write operation. This bit is a volatile latch that powers up in the LOW (disabled) state. While the WEL bit is LOW, writes to the CCR address will be ignored, although acknowledgment is still issued. The WEL bit is set by writing a “1” to the WEL bit and zeroes to the other bits of the Status Register. Once set, WEL remains set until either reset to 0 (by writing a “0” to the WEL bit and zeroes to the other bits of the Status Register) or until the part powers up again. Writes to WEL bit do not cause a non-volatile write cycle, so the device is ready for the next operation immediately after the stop condition. Leap Years Leap years add the day February 29 and are defined as those years that are divisible by 4. Status Register (SR) (Volatile) The Status Register is located in the CCR memory map at address 003Fh. This is a volatile register only and is used to control the WEL and RWEL write enable latches, read power status and two alarm bits. This register is separate from both the array and the Clock/Control Registers (CCR). TABLE 1. STATUS REGISTER (SR) ADDR 003Fh Default 7 BAT 0 6 AL1 0 5 4 3 0 0 2 RWEL 0 1 WEL 0 0 RTCF 1 RTCF: Real Time Clock Fail Bit This bit is set to a “1” after a total power failure. This is a read only bit that is set by hardware (ISL12027 internally) when the device powers up after having lost all power to the device (both VDD and VBAT go to 0V). The bit is set regardless of whether VDD or VBAT is applied first. The loss of only one of the supplies does not set the RTCF bit to “1”. On power up after a total power failure, all registers are set to their default states and the clock will not increment until at least one byte is written to the clock register. The first valid write to the RTC section after a complete power failure resets the RTCF bit to “0” (writing one byte is sufficient). AL0 OSCF 0 0 BAT: Battery Supply This bit set to “1” indicates that the device is operating from VBAT, not VDD. It is a read-only bit and is set/reset by hardware (ISL12027 internally). Once the device begins operating from VDD, the device sets this bit to “0”. Unused Bits: Bit 3 in the SR is not used, but must be zero. The Data Byte output during a SR read will contain a zero in this bit location. AL1, AL0: Alarm Bits These bits announce if either alarm 0 or alarm 1 match the real time clock. If there is a match, the respective bit is set to ‘1’. The falling edge of the last data bit in a SR Read operation resets the flags. Note: Only the AL bits that are set when an SR read starts will be reset. An alarm bit that is set by an alarm occurring during an SR read operation will remain set after the read operation is complete. 11 FN8232.4 October 18, 2006 ISL12027 TABLE 2. CLOCK/CONTROL MEMORY MAP (Shaded cells indicate that NO other value is to be written to that bit. X indicates the bits are set according to the product variation, see device ordering information) BIT ADDR. 003F 0037 0036 0035 0034 0033 0032 0031 0030 0014 0013 0012 0011 0010 000F 000E 000D 000C 000B 000A 0009 0008 0007 0006 0005 0004 0003 0002 0001 0000 Alarm0 (EEPROM) Alarm1 (EEPROM) Control (EEPROM) TYPE Status RTC (SRAM) REG NAME SR Y2K DW YR MO DT HR MN SC PWR DTR ATR INT BL Y2K1 DWA1 YRA1 MOA1 DTA1 HRA1 MNA1 SCA1 Y2K0 DWA0 YRA0 MOA0 DTA0 HRA0 MNA0 SCA0 EMO0 EDT0 EHR0 EMN0 ESC0 EMO1 EDT1 EHR1 EMN1 ESC1 0 EDW0 7 BAT 0 0 Y23 0 0 MIL 0 0 SBIB 0 0 IM BP2 0 EDW1 6 AL1 0 0 Y22 0 0 0 M22 S22 BSW 0 0 AL1E BP1 0 0 5 AL0 Y2K21 0 Y21 0 D21 H21 M21 S21 0 0 ATR5 AL0E BP0 A1Y2K21 0 4 OSCF Y2K20 0 Y20 G20 D20 H20 M20 S20 0 0 ATR4 0 WD1 A1Y2K20 0 3 0 Y2K13 0 Y13 G13 D13 H13 M13 S13 0 0 ATR3 0 WD0 A1Y2K13 0 2 RWEL 0 DY2 Y12 G12 D12 H12 M12 S12 VTS2 DTR2 ATR2 0 0 0 DY2 1 WEL 0 DY1 Y11 G11 D11 H11 M11 S11 VTS1 DTR1 ATR1 0 0 0 DY1 0 RTCF Y2K10 DY0 Y10 G10 D10 H10 M10 S10 VTS0 DTR0 ATR0 0 0 A1Y2K10 DY0 19/20 0-6 19/20 0-6 0-99 1-12 1-31 0-23 0-59 0-59 RANGE DEFAULT 01h 20h 00h 00h 00h 01h 00h 00h 00h 4Xh 00h 00h 00h 18h 20h 00h 00h 00h 00h 00h 00h 20h 00h 00h 00h 00h 00h 00h Unused - Default = RTC Year value (No EEPROM) - Future expansion 0 0 0 A1M22 A1S22 0 0 0 A1D21 A1H21 A1M21 A1S21 A0Y2K21 0 A1G20 A1D20 A1H20 A1M20 A1S20 A0Y2K20 0 A1G13 A1D13 A1H13 A1M13 A1S13 A0Y2K13 0 A1G12 A1D12 A1H12 A1M12 A1S12 0 DY2 A1G11 A1D11 A1H11 A1M11 A1S11 0 DY1 A1G10 A1D10 A1H10 A1M10 A1S10 A0Y2K10 DY0 1-12 1-31 0-23 0-59 0-59 19/20 0-6 Unused - Default = RTC Year value (No EEPROM) - Future expansion 0 0 0 A0M22 A0S22 0 A0D21 A0H21 A0M21 A0S21 A0G20 A0D20 A0H20 A0M20 A0S20 A0G13 A0D13 A0H13 A0M13 A0S13 A0G12 A0D12 A0H12 A0M12 A0S12 A0G11 A0D11 A0H11 A0M11 A0S11 A0G10 A0D10 A0H10 A0M10 A0S10 1-12 1-31 0-23 0-59 0-59 Alarm Registers (Non-Volatile) Alarm0 and Alarm1 The alarm register bytes are set up identical to the RTC register bytes, except that the MSB of each byte functions as an enable bit (enable = “1”). These enable bits specify which alarm registers (seconds, minutes, etc.) are used to make the comparison. Note that there is no alarm byte for year. The alarm function works as a comparison between the alarm registers and the RTC registers. As the RTC advances, the alarm will be triggered once a match occurs between the alarm registers and the RTC registers. Any one alarm register, multiple registers, or all registers can be 12 enabled for a match. See the Device Operation and Application section for more information. Control Registers (Non-Volatile) The Control Bits and Registers described under this section are non-volatile. BL Register BP2, BP1, BP0 - Block Protect Bits The Block Protect Bits, BP2, BP1 and BP0, determine which blocks of the array are write protected. A write to a protected block of memory is ignored. The block protect bits will FN8232.4 October 18, 2006 ISL12027 prevent write operations to one of eight segments of the array. The partitions are described in Table 3. TABLE 3. PROTECTED ADDRESSES ISL12027 None (Default) 180h – 1FFh 100h – 1FFh 000h – 1FFh 000h – 03Fh 000h – 07Fh 000h – 0FFh 000h – 1FFh BP2 BP1 BP0 ARRAY LOCK None Upper 1/4 Upper 1/2 Full Array C LOAD and X2 pins to ground (see Figure 12). The value of CX1 and CX2 is given by the following formula: C X = ( 16 ⋅ b5 + 8 ⋅ b4 + 4 ⋅ b3 + 2 ⋅ b2 + 1 ⋅ b1 + 0.5 ⋅ b0 + 9 ) pF 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 The effective series load capacitance is the combination of CX1 and CX2: C LOAD = ---------------------------------X1 X2 1 1 1 ⎛ ---------- + ---------- ⎞ ⎝C C⎠ 16 ⋅ b5 + 8 ⋅ b4 + 4 ⋅ b3 + 2 ⋅ b2 + 1 ⋅ b1 + 0.5 ⋅ b0 + 9 = ⎛ ---------------------------------------------------------------------------------------------------------------------------- ⎞ pF First 4 Pages First 8 Pages First 16 Pages Full Array ⎝ 2 ⎠ Oscillator Compensation Registers There are two trimming options. - ATR. Analog Trimming Register - DTR. Digital Trimming Register These registers are non-volatile. The combination of analog and digital trimming can give up to -64 to +110ppm of total adjustment. For example, CLOAD(ATR = 00000) = 12.5pF, CLOAD(ATR = 100000) = 4.5pF, and CLOAD(ATR = 011111) = 20.25pF. The entire range for the series combination of load capacitance goes from 4.5pF to 20.25pF in 0.25pF steps. Note that these are typical values. DTR Register - DTR2, DTR1, DTR0: Digital Trimming Register The digital trimming Bits DTR2, DTR1 and DTR0 adjust the number of counts per second and average the ppm error to achieve better accuracy. DTR2 is a sign bit. DTR2 = 0 means frequency compensation is >0. DTR2 = 1 means frequency compensation is